finished very first draft of reference docs

test/function/no_check_if_error.cpp

@@ -0,0 +1,35 @@
+
+// Test assertion error when operations to check them missing (e.g., `==`).
+
+#include <boost/contract/function.hpp>
+#include <boost/contract/guard.hpp>
+#include <boost/contract/assert.hpp>
+#include <vector>
+
+template<typename T>
+void push_back(std::vector<T>& vect, T const& val) {
+    boost::contract::guard c = boost::contract::function()
+        .postcondition([&] {
+            BOOST_CONTRACT_ASSERT(vect.back() == val); // Error (j has no ==).
+        })
+    ;
+    vect.push_back(val);
+}
+
+struct j { // Type without operator==.
+    explicit j(int i) : j_(i) {}
+private:
+    int j_;
+};
+
+int main() {
+    std::vector<int> vi;
+    push_back(vi, 123);
+
+    j jj(456);
+    std::vector<j> vj;
+    push_back(vj, jj);
+
+    return 0;
+}
+